We compared resting β-methyl-iodophenyl pentadecanoic acid (BMIPP) tomography with resting thallium-201 tomography in 28 patients with unstable angina. Tracer distribution was displayed on a polar map and compared with a normal standard deviation map obtained from a group of 12 normal subjects. The extent scores and severity scores obtained by BMIPP were significantly greater than those obtained by thallium-201. Confirmation by coronary angiography revealed the sensitivity of the methods in identifying patients to be 89% for BMIPP and 54% for thallium-201. There were significant differences between BMIPP and thallium-201 in the sensitivities of detecting postischemic jeopardized myocardium in the area supplied by the right coronary artery (RCA; 53% vs 18%, p<0.05), left circumflex artery (LCX; 78% vs 39%, p<0.025) and all 3 vessels combined (71% vs 35%, p<0.001) but no significant differences in specificity (RCA: 82% vs 64%; LCX: 70% vs 90%; and total 3 vessels combined: 75% vs 79%). In conclusion, resting BMIPP tomography is more sensitive than resting thallium-201 tomography in detecting postischemic myocardial damage in patients with unstable angina. (Jpn Circ J 1997; 61: 133 - 138)